docs: def bbfunc(wave, temperature):
      """Evaluate Planck's law in ``photlam`` (per steradian).
  
      .. note::
  
          Adapted from IRAF STSDAS SYNPHOT ``bbfunc`` task.
  
      Parameters
      ----------
      wave : array_like
          Wavelength values in Angstrom.
  
      temperature : float
          Blackbody temperature in Kelvin.
  
      Returns
      -------
      result : array_like
          Blackbody radiation in ``photlam`` per steradian.
  
      """
      x = wave * temperature
  
      mask = N.where(x > 0.0, 1, 0)
      x = N.where(mask==1, 1.43883E8 / x, 0.0)
  
      factor = N.zeros(wave.shape, dtype=N.float64)
  
      mask1 = N.where(x < LOWER, 0, 1)
      factor = N.where(mask1 == 0, 2.0 / (x * (x + 2.0)), factor)
  
      mask2 = N.where(x < UPPER, 1, 0)
      mask = mask1 * mask2
      factor = N.where(mask == 1, 1.0 / (N.exp(x) - 1.0), factor)
  
      x = x * temperature / 1.95722E5
      x = factor * x * x * x
  
      return x / (H * wave)